Method for applying metallic coatings



July 21, 1959 Filed Dec. 7, 1955 Fig.

J. B. JONES ETAL 2,895,845

mmvrons JAMES B. JONES WILLIAM c. POTTHOFF MR. sum

ATTORNEY July 21, 1959 J; B. JONES ET AL METHOD FOR APPLYING METALLIC commas 2 Sheets-Sheet 2 Filed Dec. 7, 1955 a N A 33 m m 0 \m MV- 4 M A m 6 w 0 mm my W0 5 M 1 :ES @E? as: r////// INVENTORS JAMEs a. JONES By WILLIAM c. POTTHOFF GAIL, H. M

ATTORNEY United States Patent 2,895,845 METHOD FOR APPLYING METALLIC COATINGS Application December 7, 1955, Serial No. 551,544

23 Claims. (Cl. 117-8) I This invention relates to a method for continuously applying a metallic coating to a metal surface without the use of fluxes, and more particularly, to a method whereby the surface of a metal having a relatively high melting point is coated with another metal having a relatively low melting point on a continuous strip basis by contacting a molten mass of the lower melting metal with mechanical vibratory wave energy while the molten mass is in contact with a solid surface of the metal having the higher melting point, whereby adhesion between the molten metal and the juxtaposed solid metal surface is effected.

Metallic coatings have been widely used for many purposes, including, by way of example, surface protection of an underlying metal layer, engineering performance, decoration, etc. Thus, various metal articles, as for example, journal bearings, are conventionally manufactured with a core of one metal and an. outer-surface or exposed surface of another metal. A variety of methods have heretofore been utilized to effect metallic coating of one metal upon another, such methods including hot-dipping, spraying, vapor deposition, andielectroplating. The selection of a given method is more or less dependent upon the nature of the metals to be bonded together, and the ultimate use to which the resultant bonded material is to be put.

The manufacture of bearings, such as automotive bearings, requires a bearing shell which is securely'bonded to the base metal or core metal, as such bearings are frequently subjected to and are required to withtstand high loads, and high temperatures.

Aluminum-faced steels when coated with alloys of tin and lead, or tin, lead and copper, as for example, an alloy consisting of about 90 weight percent of lead and weight percent of tin have been found to be highly useful bearing materials. At the present time such leadtin alloys are electroplated on the aluminum faced steel. While under closely regulated conditions, a fairly good coating of such alloys on the aluminum faced steels can be obtained by electroplating, there are. serious disadvantages to the use of electroplating procedures for this purpose. Thus, it has been found that electroplatingis slow, relatively expensive, and not conveniently adapted to continuous procedures. Moreover, in 'contra'distinction to the electroplating of metal elements, 'such as pure copper and the like, which has proved to be relatively simple, the electroplating of alloys comprising a plurality of metallic elements is relatively difficult and a variety of complex means and methods have provednecessary to effect simultaneous electrodeposition of the'several constituents of the bearing alloy onto the surface of the metal intended to be coated.

In addition, the coating by electroplating num faced steel presents unusual difiiculties arising from the ease with which aluminum is oxidized to oxide and the difiiculty of forming cohesively bonded metallic coatings to the aluminum oxide by electroplating of an alumi- I This invention has asanobject the provisio'n ofja meth- 2,895,845 Patented July 21, 1959 2 ed for continuously effecting a highly cohesive bond between two metals, as between two alloys, or' between an alloy and a metallic element, or between two metallic elements, one of which metals has a higher melting point than the other.

This invention has as a further object the provision of a continuous method for cohesively coating one metal with another metal.

This invention has a still further object the provision of a facile method for continuously coating onev metal onto another, in which the coating is efiected without the use. offluxes.

This invention has as adiiferent object the provision of a method whereby a firm thermally-conducting bond between a relatively low melting and a relatively high melting metal may be achieved by a continuous process.

This invention has as another object the provision of a method for coating a relatively low melting bearin metal onto a bearing core metal.

This invention has as still another object the-provision of a method for coating an alloy comprising'lead and tin onto an aluminum-surfaced steel.

These and other objects are accomplished by the 'proc: ess of the present invention in which molten metal is continuously and cohesively bonded to the surface of a metal having a relatively high melting point by exposing the molten metal,..wh-ile the molten metal is in C0111 tact with. the metal surface, to the action of mechanical vibratoryv wave energy suflicientto effect cavitation in the molten metal. The vibratory wave energy used in the process of the present invention should have a frequency of between 59 and 300,000 cycles per second, preferably a frequency of between 600 and 100,000 cy; cles per second, with an optimum frequency range of 5,000 to 75,000 cycles per second. The process of the present invention is especially useful for the bonding of relatively low melting alloys, such as lead-tin alloys to the surface of a relatively high melting metal, as for example aluminum-faced steel surfaces. a

We have discovered that in order to continuously ibond' molten metal to the, surface of a metal having a higher melting point it is essential that suflicient vibratory'wave energy be supplied to the molten metal to effect cavitation therein while the higher melting point metal is being moved beneath the transducer'bar from which the wave energy is. emanating, and that the.tip of the coupler furnishing the vibratory wave energy be immersed in the molten metal and be positioned between 0.001 to 0.085 inch from the surface of the higher melting point metal, and preferably .003 to 0.015 inch therefrom... The aforesaid range of distances is critical, and in the case of aluminum-faced steel, it is not practical to effect continuous bonding with vibratory wave energy unless the distance between the tip of the coupler and the surface of the higher melting point metal is so regulated.

We have found that it is possible in accordance with our invention to continuously bond molten metal to the surface of a metal having a melting point of about F. or more above the melting point of the metal being bonded. Thus, it ispossible in accordance with our invention to bond aluminum solder to aluminum sheet.

For the purpose of illustrating the invention there are shown in'the drawings forms which are presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown. Referring to the drawings wherein like reference characters refer to like parts:

.Figure 1 a schematic diagram of apparatus useful for the practice of one embodiment of the process of the present invention.

Figure 2 is a vertical section through one form of bonding apparatus which may be used in theprocess of the present invention.

"Figure '3 is a. plan 'view of the tip'sof a modified5arrangement of bonding apparatuswhich inay' be'used in the process of the present invention.

Figure 4 is a fragmentary elevational view ends of the apparatus shown in Figure 3.

Referring the drawings, and initially to 'Figure 1, the process of the present invention is illustratedfor the coating of a useful bearing core metal, namely aluminumfaced steel, with a bearing coating,. namely an alloy comprising lead and tin. In the specific example which will beset forth hereinbelow, thealloy'bea'r'ing coating is an alloy consisting of 90 weight percent lead and weight percent tin. However, it is, of course,'to be understood that thesubject'example is intended for illustrative'purposes, and that other metals may be used. By fnietal is meant a metallic element, or an alloy of a plurality of metallic elements.

The aluminum faced steel tobe coated by the process of the present invention 'is supplied from source 10 which comprises a supply coil of such 'steel. Source 10 may be so constructed that a strip 12 'of'steel of app'reciable length may be fed to the remainingapparatus used in the process of'the present invention, and therefore may include means well known to the 'art' for securing the terminal free 'end' of the strip 12 to the forward free end of'a reserve rollof aluminum-facedsteel. Thestrip 12 is fed between tension rollers designated 14,

the steel strip 12-'is tensione'd to the requisitc'degree of tension by rollers 14.

'From rollers 14 the tensioned'strip 12 is passed to cleaning station 16. Within cleaningstation 16 the appropriate cleaning procedure for handling the metal being processed is utilized. Such cleaning procedure will, of course, vary with the-nature and conditionof 'them'etal strip 12, and may, and in certain cases preferably should, include a wire brushing stage, wherein the metal strip is cleaned by contact with a wire-brush, such as a rotary brush17. The cleaning station inay include means for effecting chemical cleaning of the' surface of strip' '12 that'is to be coated, such as'm'eans for applying caustic or acid cleaners, and/or 'degreasing cleaners suoh astrichloroethyl'ene, which chemical treatments should preferably be followed by rinsing in "distilled water. "A preferred method for efiecting the'cle'aning of the surface of strip 12 that is to be coated is the -so-ca'lled'l'arig'ht dip process ofcleaning aluminum. One'embodiment of "this process is described in German Patent 804,054 which issued on'June 14, l951,'to Alfred Vernet.

From cleaning station -16 the 'metal' strip 121's passed to 'heater 18 which may comprise any conventional preheater, such as'an electrical or gas operated 'pre heater. Within heater 18 the temperature of the strip 12 is raised to a temperature-above the melting'point temperature of the metal to be coated on strip 12 and appreciably'below the melting point temperature of the metal strip 12. In the subject example, wherein a metal alloy consisting of 90 weight percent lead and 10 weight percent tin is utilized, pro-heating of the metal strip 12 within heater 18 to a temperature of between about 570 'F. to a temperature below the melting point of aluminum.

In certain cases it is desirable to heat the metal strip after cleaning under conditions which inhibit the formation of oxides, as for example under an inert atmosphere of a gas 'such as argon or helium, or in an 'evacuated'atmos'phere. In this case the heatingbox andthe 'c'o'ating vessel are sealed toprevent loss of the inert gas atmosphere. Accordingly, gas closures compfising'gafesf19 may be provided'in'heater 18am appucatien zene 20. H from heater 18 the metal strip '12 is passed to'th'e coating application zone designated gen'e'rallyby 'the er the tip numeral 20. Molten coating alloy designated 22 is applied to the uppermost face of strip 12, followed by the contact of the molten coating alloy with mechanical vibratory wave energy which is generated by the vibratory wave generators designated 24.

Vibratory wave energy, such as wave energy in the higher limits of the acoustic frequencies, or the lower limits of-the ultrasonic frequencies, is supplied to the molten coating alloy 22 at an energy level sufiicient to effect cavitation therein-notwithstanding the movement of strip 12. Under'such'conditions,bonding of the'coa'ting alloy 22 to the upper surface of strip 12 is achieved when the lowermosten'd of vibratory wave generator 24 is maintained from 0.001 to 0.085 inch-from the uppermost surface of 'strip 12, and preferably from 0.003 to 0.015 inch from such uppermost surface.

We do not wish to be bound by any theory as to how bonding of the coating alloy 12 is effected. However, it is our belief that the vibratory energy transmitted from generators 24 elfects this result through cavitation of the molten coating alloy 22 coupled with a transformational effect on the aluminum coating of the strip 12 whereby such coating isplaced ina state such that bonding of the molten coating alloy 22 thereto may be achieved.

In support of our belief 'we have observed that it is possible 'to effect coating of the molten coating alloy 22 to metal strip 12 under the conditions set forth above notwithstanding that metal strip 12 has not been subjected to as vigorous a cleaning pre-treatment as would lie-necessary to ensure cohesive' electroplating of the alloy components thereto.

In'the accompanying schematic Figure l, a series of three tandem arranged vibratory wave generators 24'are shown, but it is to be understood that a larger or smaller number of suchegenerators 24 may be utilized.

The construction of the vibratory wave generators-24, and the method of application of the coating alloy 22 to the strip' metal 12 within coating application zone 20 will be more fully-describedhereinbelow.

The metal strip 12 carrying bonded coating alloy 22 is removed from coating application zone 20 and is tensioned upwardly by means of tension rollers 26 and 28.

The metal strip 12 is then cooled suddenly, and the coating solidified by'being quenched through contact with quenching liquid discharged in the form of'a spray on the underside of metalstrip 12 by quenching spray generator 30.

The coated metal strip 12 is finished by having the thic'kness'bf the applied coating reduced to the exact thickness desired for 'theapplication to which the coated metal is to be put. Thus, the thickness of the coating may be regulated by first removing excess coating metal with a relatively rough-preliminary cut as by means of amilling type cutter designated 32, followed by a relativelyfine surface but as by means of a scarfingknife 34 or other tool capable-of continuously effecting surface finishing. The metal strip 12 is.passed over a support generating equipment 'for securing the molten coating 'alloy'22 to'themetal strip 12 in coating application zone '20 will not be described in detail. 'bu't'a" single'vibra'tory'wa egenerator 24 will be set forth,

The 1 description of it being understood that if a'plurality'of such vibratory wave generators -a're"'-us'ed, each generator will generally resemblethe"'othe'rs,although it"is, of course, possible 't 0, 'utilize "vibratory wave generating equipment 'having "diifre'nfstruc'tures'within coating application zone20.

The vibrato'iywave generator 24 used in the process of 'the'pfesent invention comprises amagnet'ostrictive' source orstack 40 constituting a laminated core of nickel elements. In place of nickel other materials such as the alloy Permendur which undergo magnetostriction may be used. Source 40 is provided with an inner perforation 42 through which the elements of polarizing coil 44 and excitation coil 44a: may be passed. Personnel skilled in the design and use of elastic vibratory energy will readily comprehend that ferroelectric ceramics such as barium titanate and lead titanate-zirconate can be readily substituted for nickel or Permendur.

' It will be understood by those skilled in the art that variation of the magnetic field strength of the excitation coil 44a will produce concomitant variations in the dimension of the magnetostrictive source 40, providing the polarizing coil is charged at a suitable level with DC. current, and that the frequency of the aforesaid variations, namely the expansion and contraction of the magnetostrictive source 40 will be equal to the frequency of the alternating electric current flowing'in the excitation coil 44a. The use of ferroelectric ceramics obviates the necessity for coils since these materials are caused to operate by the application of an alternating electric potential to the metallically coated surfaces of the ferroelectric ceramics.

In the apparatus herein referred to, the expansion and contraction of the magnetrostrictive source 40 will be such as to produce elastic waves in the upper frequency level of the acoustic range, such as waves having a frequency of the order of 15 kilocycles. Cooling means 46 consisting of a fan, air impeller, or the like is juxtaposed to the magnetostrictive source 40 to prevent the source 40 from become overheated.

A coupling member 48 which may be of stainless steel or the like having a relatively low thermal conductivity is fixedly secured to the undersurface of the magnetostrictive source 40 as by brazing with silver solder or the like. Coupler member 48 is threadably secured and preferably also brazed to a support clamp 52 by means of mating threads designated 50. The support clamp 52 may be raised or lowered, permitting the raising or lowering of the generator 24, and adjustment of the gap distance between the free tip end 61 of generator 24 and the upper surface of metal strip 12 to within the range 0.001 to 0.085 inch, and preferably from 0.003 to 0.015 inch.

A coupler 54 of stainless steel or other metal having a relatively low thermal conductivity is fixedly secured to coupling member 48 by threaded coupler shaft 56. The upper end of coupler 54 is provided with a water jacket 58 through which cooling water may be introduced to control the temperature of the upper end of the coupler 54. The lower end of the coupler 54 is encircled by tip heater 60 constituting a resistance coil heater, which permits the tip 61 of the coupler 64 to be raised to a temperature above the melting point of the molten coating alloy 12.

We have found that the tuned resonant frequency obtained from coupler 54 is to some degree a function of the temperature of the coupler 54. Thus, a 2% inch diameter cylindrical stainless steel coupler when driven by a 600 watt generator connected to a laminated nickel stack was found to develop a resonant frequency of 14.8 kilocycles when the coupler was at room temperature, and a resonant frequency of but 14.3 kilocycles when heated to a temperature within the range 600 to 780 F. Electronic generators are not vital to the equipment, and rotating machines such as high frequency alternators can be substituted for the electronic type of generator.

We have found that it is advantageous to have the molten coating alloy 22 loosely disposed in the form of a puddle or the like above the metal strip 12, with the free tip 61 of the coupler 54 submerged below the upper level of the molten coating alloy 12, and with additional molten coating alloy being added to the puddle as the coating alloy is gradually removed from the puddle due to its deposition on the upper surface of the strip 12.

Wehave also found it advantageous to maintain a massivenon-resonant member 62-underneath the metalstrip- 12, although the strip 12 may be operatively positioned by closely regulatedatensioning, or by the use of massive roll-. Close control of the gap distance to the ers or the like. aforesaid limits is essential regardless of the means employed to support strip 12 while it is passing beneath th free tip end 61.

The container 70 for the molten coating alloy 22 may be in the form of a trough and may be heated to keep the coating alloy molten. Molten coating alloy 22 may be automatically introduced into container 70 at the same rate that it is withdrawn by deposition onto strip 12 thereby rendering the process contniuous.

, In Figures 3 and 4 a modified arrangement of generators .is shown in which a pair of rectangular transducer bar tips 610 are spaced sidewise of each other, with a free space therebetween. v In this arrangement, coating of molten coatingme tal along two parallel bands on the upper surface of a ;metal stripwith an uncoated band therebetween may ,be achieved. Thus, although the entire upper surface of the metal strip to be coated is coated with molten coating metal, adhesion to themetal strip is effected solely in the regionbeneath the transducer bar tips 61a.

The present invention may be embodied in other specific;

metal at a temperature above the melting point of the lower melting metal and below the melting point of the higher melting metal, immersing the tip of a vibratory device insaid molten mass of metal with the lowermost end of said tip being spaced from the surface of the metal having a relatively high melting point a distance of between 0.001 to 0.085 inch, exposing the molten mass of the lower melting metal to a sufiicient amount of mechanical vibratorywave-energy having a frequency of between 59 and 300,000 cycles per second to effect cavitation in said molten mass and bonding of the molten mass tothe une derlying metal surface, and then cooling said molten mass of metal to --a temperature at which it solidifies.

2. A method in accordance with claim 1 in which the lowermost end of the tip of the vibratory device is spaced from the surface of the metal having a relatively high melting pointa distance of between 0.003 to 0.015 inch.

3. A method in accordance with claim 2 in which the frequency of the mechanical vibratory wave energy is between 600 and.l00,000 cycles per second.

4. A method in accordance with claim 3 in which the frequency of the mechanical vibratory wave energy is between 5,000 and 75,000 cycles per second. i

5. A method in accordance with claim 1 in which the lower melting metal is an alloy consisting of a plurality of metallic elements.

6. A method in accordance with claim 5 in which the alloy consists essentially of lead and tin, with the lead present in a major weight percentage.

7. A method in accordance with claim 6 in which the uppermost surface of the higher melting metal is aluminum.

8. A method in accordance with claim 1 in which the mechanical vibratory wave energy is applied while the molten mass of the lower melting metal is in a non-oxidizing atmosphere.

. 9. A method for-coating a face of a continuously moving metal strip with a metallurgically bonded lower melting metal which comprises cleaning the face of the metal strip to be coated bypassing said strip through a cleaning 7 station, then applying a: molten mass of s metal tosaid cleaned f'acea a temperature above the melting point of the lower nreltingmetal and belbw fliemelting point of thehig'h'ermeltihg metal; moving'said metal to an application zone wherein the tip of a vibratory'd'eviee-isimmersedin saidmoiten-m'ass of metal. with the lowermost end of said tip being spaced from the cleaned facea distance ofbetween 0.001 to*'.0'85 inch,

applying a suflici'ent amount of mechanical vibratory wave energyfrom thetip-of-s'aid vibratory deviceat fre- 11. A method in accordance with claim 1'0in which the frequency of the mechanical vibratory wave'energy' is between 600 and 100,000"cycles per second;

12'. A method'in accordance 'clair'n' 11' in which the frequency of the mechanical vibratory wave energy is between 5,000 and 100,000cyc1es per second.

13. A method in accordance with claim 9" in which the lower meltingmetal is an alloy consisting'of 'a' plurality of metallic elements;

14'. A method in accordance with claim 13-=-in which" thealloy consists essentially of lead and tin, with thelead present ina"ma'jorweight* percentage; I

15. A methodiin-accordanc'cwith claim 14' inwhich the metal. bein'gcoated is aluminum:

16, A method" in accordance with claim 9*'in" which the mechanical vibratory "wave energy is applied while themoltcnma'ssofthe l'ower melting metal isin a nono'xidizing atmosphere:

17. A methodfor 'continuouslybonding-a plurality 'of spaced metal coatings of ametalhaving' a relatively low meltingpoint" to the surfaceof a" moving stri'p'of' metal having a relatively high melting-point which comprises covering the" surface of the moving strip' of higher melting metal with a molten massof thelower melting metal at atemperature above the melting pointofthe lower melting" metal and below the meltin'gpoint'of'the' higher melting metal; immersing a plurality of laterallyspaced' vibratory device tips within saidmolten mass of metal with the lowermost end of eachof said tips-being spaced f'rom the surfaceof the metal'h'avinga relatively higlrmelting point a distance of between 0.001 to 0.085 inch, each of said tips being positionedabove the moving strip ofmetal, exposing the molten mass ofthe lower melting mctalto a suflicient amount of'me'chanical vibratory wave energy having a frequency of between 59 and 300,000 cycles per second to eficctcavitation in-saidmolten mass and bond ing of" the moltcn'mass' to thc'underlying-mctal surface beneath-each of said'tips', and then cooling 'said'molten mass of metal to a temperature at which it solidifies.

18 Apparatus forcontinuouslybonding a molten metal to a'mctal strip-formed from a higher melting metal, said apparatus comprising afiatbottomcd trough, an elongated upright rod suspendedabovcsaid'trough with the tip of said rod-disposed within said trough and spaced from the floor thereof a suflicient height to provide a passageway for the continuousmovement-'thcrethrough of" the metal strip of relatively-higher melting metal, the gap distance between the upper surfaeeofthe' movingmetal "strip and the rod tip being between 0.001 to 0.085" inch, heating means adjacent saidtip and abbvasaidiroughfbr heating saidtip, means for "generating vibratory energy fixedly secured-totheupper part o'f-said"elongated"upright rod, heat-exchangc'me'ans'fortoolingsaidiromdisposcd"above said heating means and b'elow said means for generating: vibratory-energy; and support means for maintaining said? rod in an upright position.

19E Apparatusfor continuously bonding a' molten mctal to a metal strip-formed from a higher meltin'g metalg saith apparatus comprising a container for the moltenmetal; meansforsupporting a continuously moving strip of the" relatively highermelting-metal within said container, anelougated rodpositioned above said last-mentioned means, the gap distance between the upper surface of the moving metal strip-and the tip of said rod being between 0.001 and 0.085 inch, means for generating vibratory energy fixedly secured to a part of said rod disposed outside" of said container for molten metal, heat-exchange means: for cooling saidrod disposed beneath the point of. engagement of'said rod with said' meansfor generating vibratory energy, and support means for maintaining said rod in an upright" position.

20; Apparatus for continuouslybonding a molten .metal to' a movingmetal strip formed from-a relatively'highen melting-metal, said apparatus comprising a container for the'molten'm'etal, meansfor supporting the moving metal strip within said container, an elongated upright rod, the gap distance between the upper surface of the moving metal strip'and the tip of the lowermost end of said rod being between 0.001- to' 0.085 inch, a magnetostrictivctransducer fixedly secured to the uppermost end of said rod, heat-exchange means for cooling said rod disposed beneath said magnetostrictive transducer, and support means-for maintaining sa'idrod in an upright position.

21. Apparatus for continuously bonding a molten metal to a metal strip formed from a higher melting metal; said-apparatus comprising a flat-bottomed trough, an elongated upright rod suspended above saidtroughwith the lowermost tip of said rod disposed within 'said trough and spaced from the floor thereof a sufficient height to provide a passageway for the continuous movement therethrough of the metal strip of relatively highermeltin'g metal, the gap distance between the upper surface of the moving metal strip and the lowermost tip of'said' rod being between 0.003 to 0.015 inch, heating means adjacent said'tip and above said trough for heating said tip, a' magnetostrictive transducer for generating vibratory energy fixedly secured to the uppermost end of-said rod, heat-exchange means for cooling said rod disposed beneath said magnetostrictive transducer and above said heating'means, and support means for maintaining said rodin'an upright position.

2-2. Apparatusfor continuously bonding a plurality of spaced bands of amolten metal-to a continuously moving metal'stripformed from a higher melting metal, said ap= paratus comprising acontainer for the moltenmetal; meansfor supporting the moving metal strip of the relatively higher melting metal, a plurality of laterally spaced upri'ght=rods, the lowermost tip of each of said rods being disposed within-the container for said molten metal-and spaced above the continuously moving strip of relatively higher melting metal, the gap distance between the upper surface of the moving metal strip and the lowermost tip of each of said rods being between 0.001 to 0.085 inch, means forgeneratingvibratory energy fixedly secured to the upper part of each of said rods, heat-exchange means for cooling each of'said rods disposed beneath said laste mentioned: means, and. support means for maintaining each of said rods in an upright position.

23. Apparatus for continuously bonding a plurality of spaced bands of a molten metal to the uppermost surface of'a met'a'l strip formed from a relatively higher melting metal, said apparatus comprising a fiat-bottomed trough; aplurality ofelongated laterally spaced upright rods suspended above said trough with the lowermost tip of each of said-rods disposed within said trough and-spaced from the-floor thereof a sufiicient height to provide a passageway-for the continuous movement therethrough of-the metalstripof relativelyhigher'melting metal, the

gap distance between the upper surface of the moving metal strip and the lowermost tip of each of said rods being between 0.001 to 0.085 inch, heating means adjacent each of said tips and above said trough for heating each of said tips, magnetostrictive transducer means fixedly secured to the uppermost end of each of said rods, and support means for maintaining each of said rods in an upright position.

2,241,789 Queneau et a1. May 13, 1941 10 Hoza Nov. 18, 1941 Plott et a1. May 4, 1943 Mann Aug. 6, 1946 Harris et a1. Ian. 18, 1949 Burns et a1 Oct. 20, 1953 FOREIGN PATENTS Germany Oct. 29, 1953 OTHER REFERENCES Crawford: Electronics 25, December 1952, pp. 102-5. 

1. A METHOD FOR CONTINUOUSLY BONDING A METAL HAVING A RELATIVELY LOW MELTING POINT TO THE SURFACE OF A MOVING STRIP OF METAL HAVING A RELATIVELY HIGH MELTING POINT WHICH COMPRISES COATING THE SURFACE OF THE MOVING STRIP OF HIGHER MELTING METAL WITH A MOLTEN MASS OF THE LOWER MELTING METAL AT A TEMPERATURE ABOVE THE MELTING POINT OF THE LOWER MELTING METAL AND BELOW THE MELTING POINT OF THE HIGHER MELTING METAL, IMMERSING THE TIP OF A VIBRATORY DEVICE IN SAID MOLTEN MASS OF METAL WITH THE LOWERMOST END OF SAIF TIP BEING SPACED FROM THE SURFACE OF THE METAL HAVING A RELATIVELY HIGH MELTING POINT A DISTANCE OF BETWEEN 0.001 TO 0.085 INCH, EXPOSING THE MOLTEN MASS OF THE LOWER MELTING METAL TO A SUFFICIENT AMOUNT OF MECHANICAL VIBRATORY WAVE ENERGY HAVING A FREQUENCY OF BETWEEN 59 AND 300,000 CYCLES PER SECOND TO EFFECT CAVITATION IN SAID MOLTEN MASS AND BONDING OF THE MOLTEN MASS TO THE UNDERLYING METAL SURFACE, AND THEN COOLING SAID MOLTEN MASS OF METAL TO A TEMPERATURE AT WHICH IT SOLIDIFIES. 